Reconstituting tobacco



Sept. 11, 1962 B. PERRIN ETAL RECONSTITUTING TOBACCO 3 Sheets-Sheet 1Filed May 3, 1961 l/vus/vfokzi .4 JMVM ATTORNEX Sept. 11, 1962 B. PERRXNETAL RECONSTITUTING TOBACCO 3 Sheets-Sheet 2 Filed May 3, 1961 j) WATToRA/Eg Sept. 11, 1962 B. PERRIN ETAL 3,053,258

RECONSTITUTING TOBACCO Filed May 3, 1961 3 Sheets-Sheet 5 3,053,258RECONSTITUTING TGBACCO Bernard Pcrrin, Lausanne, Switzerland, and GeraldMansell Horey, Deptford, London, England, assignors to Molins MachineCompany Limited Filed May 3, 1961, Ser. No. 107,519 Claims priority,application Great Britain May 20, 1960 2 Claims. (61. 131140) Thisinvention concerns improvements in or relating to a method of andapparatus for processing tobacco.

'In the manufacture of tobacco products, such as cigarettes, it iscustomary to subject tobacco leaf tovarious primary processes whichinclude stemming, conditioning and cutting of the leaf lamina in atobacco cutting machine to obtain shredded tobacco which can then beused in a normal cigarette-making machine. With regard to the stem oftobacco leaf, this is subjected to different processes, which includerolling or crushing and then cutting, so that cut rolled stem issomewhat similar to the shredded leaf lamina and can be mixed with theleaf lamina for incorporation in the cigarettes produced on thecigarette-making machine.

In the manufacture of the cigarettes, some of the tobacco productsbecome unusable for various reasons. For instance, dust is producedwhich contains minute tobacco particles, while some of the tobacco maybe so broken up as to constitute what is sometimes referred to as smallswhich are of little use for re-using in that condition in a cigarettemachine, and slivers of stem, which possess undesirable characteristics,may also be removed in a cigarette machine by winnowing.

Heretofore no way has been found of re-using any of these waste productswithout special treatment. Some proposals have been made for what iscalled reconstituting these waste products by subjecting them to variousprocesses some of which are similar to the papermaking process, in whichthey are formed into sheet with the object of using the sheet in the waythe original leaflamina was used by being shredded into fine shreds forincorporating into other shredded tobacco for use on thecigarette-making machine.

Many difficulties have been encountered in the making of this so-calledreconstituted tobacco sheet, whether it is made from waste products, orwhether it is made from the original tobacco before being subjected toany primary process as aforesaid. One difficulty is that, due to thelarge bulk of water used in reconstituting tobacco in the normalpaper-making process, a great deal of the elements which are responsiblefor the characteristic flavour of the tobacco are lost by leaching.

The present invention is concerned with a process and apparatus fortreating tobacco products, whether waste products or otherwise, all orany part of which shall be understood to come Within the term tobaccoproduct when used herein and where the context permits.

According to the present invention there is provided a method ofprocessing tobacco, comprising the steps of adding tobacco product to aliquid (such as water) to produce a solution of soluble constituents oftobacco product in the liquid, of pulping the fibrous portion of tobaccoproduct so that it is capable of retaining a desired quantity of thesolution, of concentrating the fibrous portion of tobacco product afterit has been removed from the solution to form a concentrated pulpyproduct and of arranging that the ratio of soluble constituents oftobacco product to liquid, in the liquid retained by the concentratedpulpy product, is such that the concentrated pulpy product after beingdried contains the constituents in substantially the same quantities astates tent were present in the tobacco product from which theconcentrated pulpy product was formed.

The total quantity of the soluble constituents of the tobacco productretained by the said fibrous portion may be held at a substantiallyfixed ratio to the quantity of liquid present in the fibrous portion bymaintaining the total quantity of the soluble constituents of thetobacco product in the solution present in the system at a substantiallyfixed ratio to the quantity of liquid present in the system.

Further according to the invention there is provided apparatus for themanufacture of reconstituted tobacco comprising mixing means for addingtobacco product to a liquid (e.g. water) to produce a solution ofsoluble constituents of tobacco product in the liquid, disintegratingmeans for pulping the insoluble portion of tobacco prod not so that itis capable of retaining a desired quantity of the solution,concentrating means for forming the insoluble portion of tobacco productwithin the solution into a pulpy product, and controlling means forholding the ratio of tobacco product in the liquid retained by the saidinsoluble portion of the puply product, to the quantity of liquidretained thereby, at a substantially fixed level, so that the pulpyproduct, after being dried, contains the constituents in substantiallythe same quantities as were present in the tobacco product from whichthe said pulpy product was formed.

Controlling means may be provided comprising a feedback controlcomprising a load cell or strain gauge or similar weighing device formeasuring continuously the quantity of pulpy product prior to its beingdried, a three-term controller to receive a series of signals from theload cell, strain gauge or similar weighing device and to transmitvariations in operating voltage to regulating means such as hydraulic,pneumatic or electrically operated mechanisms for feeding desiredquantities of the said tobacco product and of the said liquid into thesystem.

The disintegrating means for pulping the fibrous portion may comprise afeedback controller comprising means for feeding a specified volume ofthe mixture of the insoluble portion of the tobacco product and of thesolution into a container which is so arranged that the time taken forthe liquid portion of the said mixture (which time is afunction of thedegree of treatment of the fibrous portion), to pass through the fibrousportion, is used to provide input signal to an integrating controller,the output from which is used to regulate the treatment of the insolubleportion.

Past experience has shown that large quantities of liquid dissolve thesoluble constituents from thetobacoo product. If the excess liquid isthen run to waste some of the soluble constituents are irretrievablylost and cannot be replaced in the pulpy product. By restricting thetotal quantity of liquid within the apparatus and by avoiding thewastage of any liquid except that retained by the concentrated pulpyproduct, which amount is automatically replaced in the apparatus, it hasbeen found possible to maintain the system in a steady state in whichthe relationship between the total amount of solubles held in the liquidto the total quantity of liquid present within E=Percentage of solublesin the liquid after the steady state has been reached.

S=Percentage of soluble constituents in the dry weight of the tobaccoproduct.

Apparatus according to the invention will now be described by way ofexample with reference to the accompanying drawings, in which:

FIGURE 1 is a diagrammatic arrangement.

FIGURE 2 is an enlarged view, partly side view, partly section andpartly diagrammatic, of a portion of FIGURE 1.

FIGURE 3 is an alternative diagrammatic arrangement.

Referring to FIGURE 1, a mixing tank 1 is fed with tobacco product froma hopper 2, at the base of which is an opening 3 communicating to anarchimedean screw 4 driven by a variable speed unit 5, and with solutionfrom an open-ended pipe 6 and with liquid from a further open-ended pipe7 controlled by a valve 8 operated by an electric motor 9. Thearrangement is such that the adding of solution into the mixing-tank 1can be controlled by valve 10 which, when shut, recirculates thesolution in a manner to be described later and, when open, allows thesolution to be discharged through the open-ended pipe 6. The quantity oftobacco product fed in the mixing-tank 1 is regulated by the variablespeed unit 5 and the quantity of the liquid discharged through theopen-ended pipe 7 is determined by the amount or the period of time ofthe opening of the valve 8. Both the variable speed unit 5 and the motor9 of the valve 8 are operated by a variable output voltage from athree-term controller 11.

The mixing-tank 1 is provided with a propeller-shaped rotor 12 driven atconstant speed by a motor 13. Between the underside of the rotor 12 anda casing 14 of the mixing-tank 1 there is an annular space 15 leading toa discharged pipe 16 fitted with a valve 17 and connected to the inletof a refiner 18. Four refiners 18, 19, 20 and 21 are in series withoutlets connected through valves 22, 23 and 24 to the inlet of thefollowing unit. The refiner 21 is provided with an outletregulatingvalve 25 fitted with a motor 26 operated by a voltage from anintegrating controller 27. The output from the refiner 21 is a pulpyproduct which is fed through a control system to be described and isdischarged through an open-ended pipe 28 into a concentrator 29.

FIGURE 2 represents the control system for the valve 25. The pulpyproduct is discharged through the valve 25 into a flow-box 30 soarranged that the discharge is directed into a compartment 31 one wallof which is a weir 32. Thus the compartment 31 is maintained full andall further discharge of the pulpy product flows over the weir 32 into asecondary compartment 33 provided with an opening 34 on its bottom-sidethrough which the overflow passes to a pipe 35 connected to theopenended pipe 28. At the bottom of the compartment 31 is an opening 36connected to a pipe 37 in which a butterfly-valve 38 is operated by asolenoid 39. The solenoid is operated by a process-controller 40. Thecompartment 31 is shaped so that it contains no corners or edges. Whenthe butterfly-valve 38 is open the contents of the compartment 31 fallinto compartment 41 which is made of an insulating material such asglass or a suitable plastic and is provided with an opening 42 on itsbottom side. A flap-valve 4'3 constructed from a fine copper wire meshis pivoted at 44 and is operated by a pinion 45 which engages with arack 46 moved by a solenoid valve 47. In its normal position theflap-valve 43 covers the opening 42.

When the contents of the compartment 31 are dropped into the compartment41 a sheet of solid matter is formed on the wire mesh of the flap-valve43. Three terminals 48, 49 and are disposed in the insulated material ofthe compartment 41 so that when liquid is present within the compartment41 two electrical circuits are completed. The first is between theterminals 48 and 50 so that when the liquid level is above 48 a circuitis completed. Conversely as the liquid level drops this circuit isbroken immediately the level falls below the terminal 48. The secondcircuit is between the terminals 49 and 50. In the same way when theliquid level drops below 50 the circuit is broken. As each circuit isbroken a signal is fed into the integrating controller 27 which canthereby measure the time taken for the liquid level to fall from theterminal 48 to the terminal 50. The measured time can then be used toregulate the duration of an output voltage which will operate the motor26 and thus control the amount of opening of the regulating-valve 25.

When the liquid has drained through the wire mesh of the flap-valve 43 asheet of the pulpy product will have formed on the wire mesh and must bewashed off before the following contents of the compartment 31 can bedropped into the compartment 41. Action of the rack 46 will rotate thepinion 45 and thus move the flap-valve 43 until it covers an opening 51.In this position the sheet formed on the wire mesh can be washed off bymeans of a reflux of liquid through a pipe 52 when a valve 53 operatedby a solenoid is opened for a short period. The liquid and solids fromthe sheet of intermediate pulpy product is washed through a pipe 55which is connected to the open-ended pipe 28.

Returning now to FIGURE 1 the concentrator 29 into which the mixture ofthe pulpy product and the solution is fed is provided with a cylinder 56rotating in the direction shown by the arrow. A continuous sheet S ofthe pulpy mixture is formed on the outside of the cylinder 56 and ispicked off by a couch roll 57. A continuous felt band 58 running in thedirection shown carries the continuous sheet S over a load cell 59*which transmits back to the three-term controller 11 a continuous recordproportional to the weight of the sheet S and of the solution held inassociation with the sheet. The sheet is then transferred by known meansto the first band of a dryer 60 where the final drying takes place. Thesolution extracted through the sheet S is emptied through trunnion-ends62 and pumped through a pump 63 either to the mixing-tank 1 or back tothe concentrator dependent on whichever of valves 10 and 64 is opened.

The operation of the apparatus will now be described. The tobaccoproduct which is fed into the hopper 2 contains bundles of fibres in theform of pieces of stem or of stem sliver. The rotor 12 which is rotatingat high speed, of the mixing tank 1 acts as a breaking force on thefibre bundles. Due to the shape of the casing 14 all fibre bundlescoming into contact with the rotor are flung out by centrifugal forcewhereas individual fibres which are of lower Weight can mix freely withthe liquid and pass out of the mixing-tank through the annular space 15.The rate at which the liquid and solid constituents of the tobaccoproduct pass through the pipe 16 can be regulated by the valve 17 sincethe series of refiners acts as a pump and therefore exerts a suctionhead.

The action of the refiners 18, 19, 20 and 21 is in every way similar totheir use in papermaking i.e. individual fibres are beaten andfibrillated until they are in a condition to be made into shcet form. Inaddition the degree to which the fibres are beaten and fibrillateddetermines the quantity of free solution they will retain under a givenset of physical conditions. Consequently the control of the valve 25which determines the rate at which the fibres are treated and thus thedegree to which they will retain the solution, is of great importance.This control is exercised by measuring the time for a known quantity ofa mixture of the solution and of the fibres and solids, as the mixtureis delivered by the valve 25 to the flow-box 30, taken to drain througha sheet formed by the same fibres and solids while the liquid levelfalls from the terminal 48 to the terminal 50. The sequence ofoperations is as follows:

As soon as the liquid in the compartment 31 reaches.

the level of the top of the weir 32 a signal is transmitted to theprocess controller 40 through a contact 61. A similar signal must alsobe received from the solenoid 47 to indicate to the process controllerthat the flap-valve 43 is in its correct position, at the bottom of thecompartment 41. On receipt of these two signals two operating voltagesare transmitted from the process controller, one to close the valve 25and the other to open the butterfly-valve 38. As soon as a predeterminedinterval of sufiicient duration to allow the contents of thecompartrnent 31 to pass to the compartment 31 has elapsed, two reversingvoltages are transmitted to open the valve 25 and to close thebutterfly-valve 38. As soon as the circuit between the terminals 43 and56 is broken an integrating timer in the controller 27 is started and isagain stopped When the circuit between the terminals 5% and 49 isbroken. An output signal dependent on the elapsed time is thentransmitted to the motor 26 which accordingly controls the opening ofthe valve 25 to the required degree. At the same time a simple signal toindicate the completion of the timing cycle is passed by the controller27 back to the process controller 40 which then transmits an operatingvoltage to the solenoid 47, thereby movingthe flap-valve to its Washingposition over the opening 51. A further operating voltage is then passedto the solenoid 54 thereby opening the valve 53 and allowing the refluxwashing of the wire mesh. After a predetermined interval the operatingvoltage is cutoff and the solenoid 54 closes the valve 53. Finally thevoltage to the solenoid 47 is cut-off so that the flap-valve 43 returnsto its position at the bottom of the compartmen 41. The system is now ina condition to start the next sequence of operations.

The sheet S, formed on the cylinder 56 of the concentrator 29 willcontain fibres and solids treated so that they will retain a constantratio of the solution to the dry weight of the fibres and the solids.Consequently the continuous weight signal produced by the load cell 59as the sheet of the intermediate pulpy product passes over the load celland transmitted to the three-term controller 11 can be split up in thethree-term controller into two components, one corresponding to theweight of the solids and the other to the quantity of liquid held by thesolids. The first component can then be used to regulate the operatingvoltage fed from the process-controllerto the variable-speed unit 5.Similarly the second component of the continuous signal from theload-cell is used to regulate through a change-over switch the quantityof liquid added back into the apparatus either at the valve 8 or througha valve 65 operated by a motor 66. Both components are used to givethree-term control i.e. proportional, derivative and integral, therebyachieving the desired effect of feeding back into the apparatus equalquantities of the tobacco product and of the liquid as are removed fromthe apparatus in the form of the pulpy product and the liquid which issubsequently evaporated in the drying stage.

For example, reconstituted tobacco can be made in the following manner.A solution is prepared by adding tobacco dust to water in the mixingtank 1 and stirring by means of the rotor 12 for five minutes until thesoluble constituents of the dust have entered into the solution with thewater. The slurry produced by the mixture of the insoluble dustconstituents and the solution can then be pumped through the series ofrefiners 18 to 21 to the concentrator 29 which can then be used as afilter, with the solution being pumped back to the mixing-tank via thepump 63, the valve 19 and the open-ended pipe 6. The insoluble dustconstituents will form on the outside of the cylinder 56 and specialarrangements must be made for their removal since such dust constituentswhich may form a pulpy layer on the cylinder will not of themselves forma commercially satisfactory sheet and, therefore, cannot be picked offthe cylinder 56 by the couch-roll 57. The insoluble dust constituents ontheir own are Waste products and are not in this example put to anyfurther useful purpose in the process being described once the dust hasbeen used for the extraction of its soluble constituents.

- The operation just described will then be repeated but, instead ofusing water, fresh tobacco dust is added to the solution alreadyextracted in the concentrator 29 and returned to the mixing-tank 1.After each extraction of the soluble constituents from the dust thestrength of the solution is checked. This can be done by taking a sampleand using any suitable laboratory method.

The extraction process is repeated, until the solution obtained contains8% of soluble constituents. It is also necessary that there should besufiicient of this solution to ensure that when the process of makingreconstituted tobacco begins, the Whole system will be filled by thissolution and tobacco product added to it for the purpose of making areconstituted product. It should be remembered that as soon as thetobacco product is added to the solution soluble constituents will bedissolved out of it and will pass into the solution so that in effect,on the addition of the tobacco product at the commencement of theprocess for making reconstituted tobacco, the solution will becomestronger. However in this example that point is ignored.

In preparing the solution arrangements should be made for extracting andrecovering liquid from the insoluble dust constituents (e.g. by pressingthe slurry) after they are removed from the cylinder 56 of theconcentrator 29, since considerable quantities of the solution wouldotherwise be lost.

Once the required quantity of the solution at a strength of 8% has beenprepared it will be possible to feed tobacco product into the apparatusand produce reconstituted tobacco by the apparatus in the mannerdescribed hereinbefore. The tobacco product can be a mixture of shortsand winnowings with a total soluble content of 40% as determined by anysuitable laboratory method and expressed on a dry weight basis. If theconcentrator is then adjusted by a known method, either by regulatingthe difference of level between the liquid outside and the liquid insidethe cylinder or by changing the effective length of a series of suctionlegs arranged inside the cylinder, and not shown in the drawing, thequantity of the liquid retained by the fibrous portion of the tobaccoproduct after it has been suitably treated in the refiners 18 to 21, canbe modified to be five times the weight of the fibrous portion itself.

It Will be seen that the conditions quoted in this example comply withthe steady state conditions hereinbefore stated in the formula:

E=SQ In the example S=pcrcentage of soluble constituent in the dryweight of the tobacco product (in the example this Was 40%) Q=proportionof the dry weight of fibrous portion of the tobacco product to theweight of liquid retained by that weight of fibrous portion (in theexample this was /s) and this figures checks with the solution strengthwhich was to be made up before the apparatus was started up forproduction.

If the controls already described are now put into operation, i.e. acontrol to maintain the ability of the fibrous portion to retain fivetimes its own weight of liquid and a control to ensure that the weightof water and tobacco product fed into the apparatus is the same as thetotal weight of water and pulpy product leaving the concentrator, thefinal product after drying will contain substantially all thoseconstituents, whether soluble or insoluble, that were present in thetobacco product.

In this example no steps were described to prevent fermentation of thesugar content of the soluble constituents. It should be understood thatsuch steps should be taken since, unless complete sterilization of air,water and tobacco product can be achieved, general ambient conditionsmust sooner or later be met when fermentation must take place. If thesugars present (up to approx. 20% of the dry Weight of the tobaccoproduct) are converted to carbon dioxide and alcohol then the smokingqualities of the resulting reconstituted tobacco will be irretrievablyspoilt. Fermentation or other deleterious action originating frommicroorganisms can be prevented by many known methods such as the addingof inhibiting agents such as formaldehyde or benzoic acid to thesolution, or by the destruction of all forms of microorganism as soon asthey appear within the apparatus by such means as refrigeration,ultrasonic vibrations, radiation from a radioactive source and by otherknown means.

Fermentation as is well known can start in the course of a very shorttime, even in the course of one to two hours in suitable conditions andit is therefore important in a process such as the present to ensurethat some steps are taken to inhibit fermentation of the ultimateproduct produced by the process. The apparatus according to the presentinvention will not be really satisfactory unless such suitable steps toprevent fermentation etc. are taken.

In addition to fermentation a precipitate forms in the solution afterthe elapse of a period of time, usually within the range of 24-72 hours.This precipitate is formed of very small particles which, if allowed toremain within the solution, cause clogging up of filter cloths and thelike. It has, therefore, been found necessary to incorporate acentrifuge in the apparatus and to locate it at a position so that thesolution enters the centrifuge before it enters the concentrator 2.9.The particles of the precipitate collected by the centrifuge can then bereturned to the final product by any known method, such as spraying ontothe sheet S on the continuous felt band 58. The centrifuge and sprayingapparatus being of known design and not illustrated in FIGURE 1.

In FIGURE 3 in which like reference numbers refer to like parts there isshown an alternative apparatus in which the production of reconstitutedtobacco is achieved by the use of a batch process. The method andapparatus described hitherto, and shown in FIGURES l and 2, refer to acontinuous process for the production of this same product. In the batchprocess shown in FIGURE 3 a definite quantity of tobacco product is fedin the mixing-tank 1 and is converted into reconstituted tobacco beforeany further quantities of either tobacco product or of liquid are fedinto the system. Once the processing of one batch has been completed andall the fibrous portion has been converted into sheet S and has enteredthe dryer 60, a further batch of tobacco product can be fed into themixing-tank.

Since the process is of the batch type the relationship between thetotal quantity of the soluble constituent of tobacco product and thequantity of liquid within the system will not remain constant during thetime taken to process any one batch. This relationship will, however,remain at a steady level between any two different batches for identicalperiods of time within the time taken for the processing of the batches.Thus in each batch the steady state percentage E will be reached afterthe treatment of the fibrous portion has been completed and before thesheet S starts to form on the cylinder 56 of the concentrator 29.

In FIGURE 3 the means for effecting control of the process are notshown. These controls might comprise the testing of the specific gravityof the solution within the system using a hydrometer and a drainage testfor the fibrous portion using an instrument of a known type such as aSchopper-Reigler Tester. The figure obtained from such tests would thenbe compared with desiredvalue figures and any differences used to adjustthe strength of the solution or to modify the time of treatment of thefibrous portion.

What we claim as our invention and desire to secure by Letters Patentis:

l. A method of producing reconstituted tobacco, comprising the steps ofadding tobacco product to a liquid to produce a solution of solubleconstituents of tobacco product in the liquid, pulping the fibrousportion of tobacco product in the said solution so that it is capable ofretaining a desired quantity of the said solution, removing theinsoluble portion of said tobacco product from said solution,concentrating the insoluble portion of tobacco product after it has beenremoved from the solution to form a pulpy product and so controlling theratio of soluble constituents of tobacco product to liquid in the liquidretained by the said pulpy product that the said pulpy product afterbeing dried contains substantially the same quantities of solubleconstituents as were present in the tobacco product from which the saidpulpy product was formed.

2. A method as claimed in claim 1, whereby the total quantity of thesoluble constituents of the tobacco product retained by the saidinsoluble portion is held at a substantially fixed ratio to the quantityof liquid present in the insoluble portion by maintaining the totalquantity of the soluble constituents of the tobacco product in thesolution present in the system at a substantially fixed ratio to thequantity of liquid present in the system.

References Cited in the file of this patent UNITED STATES PATENTS1,534,713 Humphrey Apr. 21, 1925 2,048,624 Roselius July 21, 19362,582,075 Severi Ian. 8, 1952 2,753,872 Bowles July 10, 1956 2,805,667Von Bethman Sept. 10, 1957

